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Peabody Sage Creek Mine March 2011 <br />SL-1 Phase 11 Bond Release Request <br />data. Obviously, all hit herbaceous cover data (i.e., multiple hits combined) would not be as <br />affected. The sagebrush reference area, without the structural characteristics of the mountain <br />brush, does not have this issue and first hit herbaceous cover sample adequacy with <br />reasonable sample sizes is attainable. <br />To address this, a proposal was made to CDRMS in 2009 by ESCO Associates on behalf of <br />Seneca Coal Company to use all hit herbaceous cover as the primary basis for sample <br />adequacy in the mountain brush type. From there, adjustments and a ratio procedure (the ratio <br />of first hit herbaceous cover to all hit herbaceous cover) is applied to the data with additional <br />sample adequacy checks made during the process. The final ratio value is used to return the <br />all hit herbaceous cover mean to the first hit herbaceous cover basis needed to be used in the <br />weight averaged calculations for the success standard. For greater detail on the basis and <br />calculations, please refer to the discussion in the revegetation success evaluation report by <br />ESCO Associates included in Attachment E - Revegetation Supporting Documentation. <br />Particular attention should be made to the text of the report beginning on page 10, Table 6-4 <br />• in Appendix 6 and the correspondence with CDRMS in Appendix 7. <br />Calculation of 90 percent of the cover performance standard appropriate for 2010 sampling is <br />demonstrated below and is based on the following information: <br /> Allowable Herbaceous <br />Vegetation Type % of Pre-mining Area <br /> Cover on a first-hit basis' <br />Mountain Brush 12.4 83.0 <br />Sagebrush 44.7 17.0 <br />Herbaceous cover adjusted by subtracting noxious weeds and annual/biennial plant cover in <br />excess of 10% of the remainder. <br />2 Value determined from the ratio of first hit herbaceous cover to all hit herbaceous cover <br />(see Table 6.4 in Appendix 6, 2010 revegetation success evaluation report) <br />2010 Mountain Brush Reference Area First-hit Allowable herbaceous cover 12.4 x 2 = 24.8% <br />2010 Sagebrush Reference Area First-hit Allowable herbaceous cover 44.7 x 2 = 89.5% <br />u <br />9